Valves for use with various kinds of fire apparatus are well known in the art. Such valves are used to direct fire extinguishing fluids, such as water and water-foam combinations, onto fires. Such valves may be, for example, attached to the ends of hoses that are transported by fire pump trucks. Many different kinds of fire fighting nozzles are known in the art. One example of a fire fighting nozzle is shown and described in U.S. Pat. No. 4,589,439 (“the '439 patent”). The '439 patent issued to Robert W. Steingass on May 20, 1986, and was assigned to Task Force Tips Incorporated, the assignee of the present application.
The '439 patent describes a fire fighting nozzle that includes a receiver section and a coaxial, tubular body section. A flow control valve assembly is enclosed within the receiver section and the tubular body section. As may best be seen in FIGS. 1–3 of the '439 patent, the flow control valve assembly includes a tubular sliding valve member which is reciprocally and rotatably mounted in the receiver section. The tubular sliding valve member moves towards and away from a valve seat.
When moved in a forward direction, the tubular sliding valve member is moved into an abutting relationship with the valve seat. This prevents the discharge of fluid from the nozzle. In contrast, when the tubular sliding valve member is moved in a rearward direction, the valve member is moved out of abutting relationship with the valve seat. In this rearward position, an annular opening is formed between the valve member and the valve seat. The fluid can then be discharged through this annular opening.
This forward and rearward movement of the sliding member is initiated by the corresponding forward and rearward movement of a handle. The handle is secured to the receiver section by means of a disc that is contained within a mating bore formed in the receiver section. One such disc is shown in FIGS. 5 and 7 of the '439 patent, and its mating bore is shown in FIG. 6 of the '439 patent. Other functionally similar discs are used in connection with other, current fire fighting nozzles. These discs, one of which is depicted as Prior Art in FIG. 2A of this specification, have certain deficiencies.
For example, the Prior Art disc shown in the attached FIG. 2A includes a pair of drag nubs, both of which are shown on the right side of that Figure. These drag nubs are spaced one hundred and eighty degrees apart from each other. Each of these drag nubs is contained in one of two separate radial cavities extending from, and formed between, a central hole of the disc and the perimeter of the disc. When a trunnion screw is inserted into this central hole and fastened to the disc, the tapered end of the screw pushes or “cams” the drag nubs radially outwardly, and into contact with the walls of the mating bore in the receiver section of a fire fighting nozzle assembly.
A handle is used to move the slide valve into and out of engagement with the valve seat. The handle is attached to a disc, and the movement of the handle coincides with rotation of the disc. Friction created by the contact between the drag nubs and the walls of the mating bore is desirable. That friction creates the sensation of a drag on the handle when it is moved in a forward or rearward direction, providing the handle with a sense of heft. Moreover, this drag helps to prevent the inadvertent and unintended movement of that handle. Such inadvertent movement can occur as a result of forces encountered in the rugged conditions of use, and as a result of the water pressures attributable to high water discharge volumes, that are typically encountered during fire fighting.
While such a prior art disc is generally reliable, failures occur in approximately two units annually per thousand units in the field. The failures occur as a result of the structures found in these discs. Specifically, these prior art discs are held in place with a retaining ring, as may also be seen in FIG. 2A. If the disc should fail in the field, its removal from the receiver section is virtually impossible. Even if it were possible, however, such removal would irreparably damage the retaining ring, the disc, and the receiver section. Specifically these prior art discs are permanently held in place with a captive retaining ring. Failure of the disc can occur if the handle is deformed by a severe blow. Rotating the handle can cause the disc to wear inside its bore, or against the retaining ring. The disc no longer rotates with the desired drag, as byproducts of the wear and subsequent corrosion accumulate. Such wear and corrosion can also cause the retaining ring to expand fully out of engagement with the groove on the disc. If this happens, the disc can move out of its mating bore, causing loss of engagement of the disc with the hollow receiver section. As a result, the valve cannot function. The practical result of these deficiencies is that any failure of the prior art disc requires that the entire hollow receiver section member be returned to the manufacturer, and replaced.
Thus, it would be desirable to design a new disc that would overcome the disadvantages of the current, prior art discs. It would also be desirable to design a disc that, when broken or defective, could be readily removed from the receiver section, and be replaced with a new disc.